The present invention relates generally to printers and, more particularly, to printers using an ink ribbon cassette in which an ink ribbon is positioned to face a printing head within the range of reciprocation of the printing head.
An ink ribbon cassette of the prior art has a pair of arms integrally extending from opposite end portions thereof, the cassette case being longer than the reciprocating range of the printing head. Ribbon take-out and take-in slits are formed in the ends of the respective arms for exposing a portion of an ink ribbon contained within the cassette. Thus, the printing head and the ink ribbon are positioned to face each other within the range of reciprocation of the printing head while exposing the ink ribbon to the outside between the ribbon take-out and take-in slits.
In case, however, such a prior art ribbon cassette is used in a printer having a long range of reciprocation of the printing head, the cassette case has to be elongated. This, in turn, enlarges the distance between the ribbon take-out and take-in slits so that the ink ribbon portion exposed between the ribbon take-out and take-in slits becomes slackened. The slackening of the exposed ink ribbon portion alters the facing positional relationship between the printing head and the ink ribbon. This is disadvantageous in that the printing head and the ink ribbon fail to accurately face each other. In the prior art, this disadvantage is coped with by enlarging the width of the ink ribbon which has the drawback of increasing the thickness of the ribbon cassette. This disadvantage is especially serious in the case of using a multi-color ink ribbon having a plurality of lengthwise extending color bands. When using a multi-color ink ribbon, a color band switching device is used to shift the ribbon so that different color bands face the printing head, and the positional relationship between each color band and the printing head is displaced as the ribbon slackens thereby making it difficult if not impossible to perform the desired multi-color printing operation. For making multi-color prints of high quality, strict alignment of the positions of the ink ribbon and printing head is indispensable.